1. Field of the Invention
The present invention relates to an illumination device for visual inspection and a visual inspection apparatus.
2. Description of the Related Art
Various visual inspection apparatuses are proposed that image inspection objects with imaging apparatuses and inspect the inspection objects on the basis of obtained images. The visual inspection apparatuses are provided with an illumination device for visual inspection that irradiate illumination light on the inspection subjects.
As one of such visual inspection apparatuses, a visual inspection apparatus employing a so-called optical cutting method is proposed that projects a laser beam on an inspection object while scanning the laser beam on the inspection object with an illumination device for visual inspection to perform imaging and obtains a three-dimensional image of the inspection object on the basis of obtained image data (see JP-A-2000-193432).
However, when the optical cutting method is used, there is a drawback in that the visual inspection apparatus is large because the illumination device for visual inspection projects the laser beam while scanning the laser beam.
Therefore, it is conceivable to use a photometric stereo method (see JP-A-2001-245323) for obtaining three-dimensional data of an inspection object from plural image data obtained by changing an irradiation direction of a light source with respect to the inspection object.
This is because, in the photometric stereo method, the irradiation direction of the light source with respect to the inspection object only has to be changed by switching plural light sources and the configuration of an illumination device for visual inspection is simplified compared with the illumination device for visual inspection that scans the laser beam.
An illumination device for visual inspection for performing visual inspection using the photometric stereo method is proposed (see JP-A-2005-17234).
When the visual inspection of the inspection object is performed in this way, an illumination device for visual inspection having a different configuration is necessary according to a method for obtaining an image.